/Engine/Source/Runtime/GeometryCore/Public/MeshQueries.h
bounding box of subset of triangles of Mesh
template<typename EnumerableTriListType> static [FAxisAlignedBox3d](API\Runtime\GeometryCore\FAxisAlignedBox3d) GetTrianglesBounds ( const TriangleMeshType & Mesh, const EnumerableTriListType & Triangles, const FTransform & Transform )